542 
W. L. WILLIAMS. 
acquired immunity to a severe pestilence, to be again followed 
when the general conditions of the country are favorable to dis¬ 
semination ; animal numbers have increased, and the disease in 
some focus has found favorable conditions for luxurious develop¬ 
ment, when the disease again spreads over a large area as a 
great epizootic. 
The distribution and character of other diseases are largely 
determined by the prevailing use to which animals are put, thus 
infectious abortion of cows predominates in dairying regions and 
far less frequently in localities devoted to the breeding of beef 
cattle. Again other diseases may exist without prejudice to the 
native animal in a country where it is indigenous, and become a 
virulent pestilence once it oversteps its indigenous territory ; or 
susceptible animals are imported into its territory, like Texas 
fever and rinderpest. 
Coming to the brief list of diseases we have selected to 
specially consider, first, in order of arrangement, is glanders, 
one of the longest known, most carefully studied and most 
widely disseminated diseases of animals ; running an indefinite, 
erratic course, assuming multidinous forms, and offering on the 
whole, one of the most interesting subjects from the standpoint 
now viewed. Glanders among solipeds is more or less prevalent 
in every country so far as known save Australia, irrespective of 
temperature, humidity, altitude, or other climatic conditions. It 
attacks its victim in spite of food, housing, care, age, or breed, 
yet its prevalence, transmissability, character, and duration, are 
all as susceptible to the influence of such, as is the most delicate 
barometer to changes in atmospheric pressure, and becomes so 
changed in aspect that there is no resemblance in any way save 
bacteriologically between a series of cases. 
Fleming (*) notes that the disease is highly prevalent in 
Continental Europe and northern and eastern China, rare in 
South Africa, unknown in India, except as an imported affection, 
and coming, as a rule, from Australia, where the existence of 
the disease is denied ! He also quotes Liguistin, as stating that 
the disease was unknown in Mexico until introduced by the 
